Advanced Recon, by Palladium, for their encounter charts.
I have it, and have looked it over, a very long time ago. Don't recall what the combat rules are like, but the charts alone make it worth the purchase, even if you use other rules for the combat, and don't use their combat rules, since it is a RPG set.
Ah, I see, you also need the Recon Core Rulebook, or the Revised Recon RPG book for combat, and working out the players' and NPCs' stats.
I've read good things about Grunt too, which is another RPG. Supposedly, their morale rules are quite realistic for the period. Don't know much about it otherwise. This one is all-inclusive.